George r



PA TENTED JAN. 12, 1904.

e. R. DAVISON.

ELECTRIC ARG LAMP.

APPLIOATION FILED MAY 8, 1903.

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WITNESSES.-

unms ravens co.. morouma. wm-(mcwu. o. c.

A No. 749,268.

UNITED STATES Patented January 12, 1904.

PATENT OFFICE.

GEOEG YE. nAvisoN, oF PITTSFIELD, MASSACHUSETTS, Ass'IeNoR To STANLEY ELECTRIC MANUFACTURING COMPANY, oF PITTSFIELD, MASSACHUSETTS, A CORPORATION oF NEw JERSEY.

ELECTRIC-ARCTLQAMP.

SPEGIFICATION forming part of Letters Patent No. 749,268, dated January 12, 1904.

Application filed May 8, 1903. Serial No. 156,210. (No model.)

V I tain new and useful Improvements, in Are- Lamps, of which the following is a specifica- 8 tion.

My invention relates to arc-lamps of the closed-arc type. In such lamps the efiiciency I0 and life of the carbonsdepend chiefly on preventing the access of cold air to the arc.

The object of my invention is to provide means for preventing in greater measure the access of cold air to the arc than has been possible with former structures, and thus to increase the steadiness and efficiency of the arc and the life of the carbons.

Referring to the drawings, Figure 1 shows a structure embodying my invention; and Fig. 2 shows a cross-section, on a slightly-reduced scale, on the line w w in Fig. 1.

A represents a plate secured to the frame of the lamp by rods B B. C is the inner globe, which is supported by wire D, which is pressed upward by springs E E, surrounding rods B Thus globe C is pressed against plate A, making a practically air-tight joint. Since globe C is closed at the bottom, the only place where leakage if 3 of air can take place is where upper carbon F passes through plate A. Secured to plate A and surrounding upper carbon F is the cap Gr, which is held away from plate A by bosses g g, thus leaving a thin layer of air between i plate A and cap Gr. Cap Gr extends not quite I to the inner surface of globe C, thus leaving a thin ring of air between cap G and globe C.

. I The upper part of cap, Gr is composed of thin layers of mica H, which permit a practically l 4 air-tight fit around upper carbon and insu- Lower.

late cap G from the upper carbon.

carbon F is supported from cap G by rod I. J is the lead for the-lower carbon, passing through plate A and insulated therefrom. With the construction above described it is obvious that what little air is drawn in by the pumping of the upper carbon passes in between upper carbon F and plate A and does not enter the globe C directly. It must pass through the thin passage over and around cap 5 G and in its passage is-thoroughly heated. Thus no cold air can reach the arc to the detriment ofefiiciency and carbon life.

Although globe C is closed at the bottom so that no air can enter, the lamp may be read- 5 5 ily trimmed by pulling down wire D, swinging it aside, and removing globe C. Thus a structure is provided in which the leakage of air is reduced to a minimum without sacrificing facility for trimming.

I do not desire tolimit myself to the particular construction and arrangement of parts here shown, since changes therein which do not depart from the spirit of my invention and which are within the scope of the append- 5 ed claims will be obvious to those skilled in the art.

Having thus fully described my invention, I claim as new and desire to protect by Letters Patent 1. In an arc-lamp, a globe adapted to transmitlight, acover-plate therefor, acarbon passing through said plate and extending into said globe, and a cap closely surrounding said carbon and supported below said plate so as to form a thin space between said plate and said cap extending from said carbon nearly to the inner periphery of said globe.

2. In an arc-lamp, a globe adapted to transmit light, a cover-plate therefor, a carbon passing through said plate and extending into said globe, and a cap closely fitting around said carbon and supported below said plate so as to leave a thin space around said carbon between said plate and said cap. 8 5

3. In an arc-lamp, a globe adapted to transmit light, a cover-plate therefor, a carbon passing through said plate and extending into said globe, and a shield composed of thin insulating-sheets closely surrounding said carbon and 9 supported below said plate so as to leave a thin space between said plate and said shield.

4:. In an arc-lamp, a globe adapted to transmit light, a cover-plate therefor, a carbon passing through said plate and extending into said globe, and a cap closely surrounding said carbon and extending nearly to the inner surface of said globe, said cap being supported below said plate so as to leave a thin space between said cap and said plate.

5. In an arc-lamp, a globe adapted to transmit light, a cover-plate therefor, a carbon passing through said plate and extending into said globe, and a shield supported below said plate composed of thin insulating-sheets closely surrounding said carbon and extending nearly to the inner surface of said globe.

6. In an arc-lamp, a globe adapted to transmit light, a cover-plate therefor, a carbon passing through said plate and extending into said globe, and a cap supported below said plate and closely surrounding said carbon, the part of said cap immediately around said carbon being composed of mica sheets.

7. In an arc-lamp, a globe adapted to transmitlight, a cover-plate therefor, a carbon passing through said plate and extending into said globe, and a cap, closely surrounding said carsaid cap from said carbon nearly to the inner surface of said globe.

8. In an arc-lamp, a globe adapted to transmit light, a cover-plate therefor, a carbon passing through said plate and extending into said globe, and a cap closely surrounding said carbon and supported below said plate so as to form a passage between said plate and said cap from said carbon nearly to the inner surface of said globe, said cap having a downwardly-projecting flange at its periphery so as to form a thin space between said cap and said g obe.

Signed at Pittsfield, Massachusetts, this 5th day of May, 1903.

GEORGE R. DAVISON.

Witnesses:

L. A. HAWKINS, R. E. HAYNES. 

